Former Tour de France champion Jan Ullrich of Germany is returning his Swiss cycling federation license to protest his treatment in connection with a Spanish doping probe.

Ullrich, 32, said this does not mean he is quitting the sport. He is contacting other cycling federations for a license for 2007.

Ullrich is a German, but lives in Switzerland and has been racing with a Swiss Cycling license. He was barred from competing in this year's Tour de France after being linked to a list of cyclists who allegedly had contact with a Spanish doctor accused of running a blood-doping clinic in Madrid.

Ullrich has denied any wrongdoing, but he was fired by his T-Mobile professional team. He has accused Swiss Cycling of having a "slanderous attitude" toward him and of waging a "media campaign" against him for months.